Boulder

Boulder
ZZT-OOP name	boulder
Internal ID	24 (0x18)
Character	#char 254 ■ (0xFE)
Category	terrain
Stats?	no
Other traits
Effect on movement	pushable
Destructible?	no
Uses ZZT-OOP color names?	yes

Boulders are a pushable terrain element.

Boulders can be pushed in any direction and are an important element in slider puzzles. However, they cannot be pulled by the player, meaning that it is easy for boulders to become stuck in a corner or against a wall. Boulders cannot be destroyed by the player, so a stuck boulder in a game can often lead to a softlock.

Boulders keep their background color when they move, although this is not noticeable unless STK colors are in use. This behavior disappears if the boulder is given stats.

Erasure of fake walls

Boulders leave empties behind them when they are moved. This can be an issue for games that use fake walls as floors, as pushing a boulder across a colorful floor will erase a black trail across the floor. This erasing behavior happens because boulders lack stats by default, and thus lack a way to track their under tile. Other statless pushables (ammo, gems, keys, and sliders) also exhibit this erasing behavior, though it is more noticeable with boulders because boulders are more easily manipulated into areas of a board that have fake walls.

This erasing behavior can be eliminated by giving the boulder stats, though the number of boulders that can be treated this way is limited by the board's stat limit.